It is common knowledge that filled pasta, such as ravioli, comprises a filling that is wrapped in and/or surrounded by a portion of thin, flat dough.
Two overlapping portions of thin, flat dough are used to prepare ravioli, with a suitable quantity of filling inserted between them. The two portions of dough are then pressed and joined around the filling and along the edges, then cut to separate the ravioli from one another.
Ravioli and other types of filled pasta can be prepared at home.
Preparing ravioli normally involves:                preparing and rolling out a thin layer of dough;        preparing the filling and placing it in small portions, generally in equidistant positions, on the surface of the dough;        placing a second thin layer of dough over the portions of filling and the previous layer of dough;        pressing the two layers of dough together around the portions of filling; and        cutting the two layers of dough pressed and joined around the portions of filling, normally with a knife or pastry wheel, so as to separate them into individual parts consisting of two dough layers joined together, each enclosing a portion of filling.        
This procedure has several drawbacks:                it takes a considerable amount of time to collect each portion of filling from the filling mixture and place it on the thin layer of dough;        it is not easy to measure equal quantities of filling, with the result that some ravioli contain more filling than others;        it is not easy to position the individual portions of filling on the thin layer of dough at equal distances from one another;        it is not easy to position the individual portions of filling so as to leave an adequate—no more nor less than necessary—amount of dough around the individual portions of filling; it is not easy to produce ravioli or filled pasta all of the same shape and size; and        it is not easy to press the dough adequately around the individual portions of filling so as to ensure that the ravioli or filled pasta do not come open when they are cooked.        